Drug sequence does not up breast cancer survival

NEW YORK (Reuters Health) - After surgery for breast cancer, adding tamoxifen -- either before or after treatment with letrozole -- does not help women live longer free of disease, researchers report in Thursday's issue of The New England Journal of Medicine.

Both letrozole and tamoxifen help prevent hormone-driven breast cancer from recurring. Letrozole interferes with estrogen production, while tamoxifen blocks estrogen's ability to bind to estrogen receptors on breast cancer cells.

Prior research has shown that letrozole alone is more effective than tamoxifen alone in improving "disease-free" survival in postmenopausal women with hormone-driven early breast cancer.

Whether survival might be improved further by giving the two drugs in sequence was unclear.

To investigate, Dr. Henning Mouridsen of Rigshospitalet in Copenhagen and colleagues determined the outcomes of 6182 women who were randomly assigned to receive letrozole, tamoxifen, letrozole then tamoxifen, or tamoxifen then letrozole.

During a median follow-up period of about six years, disease-free survival in the sequence groups was no better (or worse) than that seen in the letrozole only group.

In fact, compared to the letrozole only group, more early recurrences were noted in women who received tamoxifen followed by letrozole, the researchers found.

The researchers also examined letrozole versus tamoxifen in 4922 women. Confirming previous reports, disease-free survival was better with letrozole than with tamoxifen.

There was also a trend toward better overall survival with letrozole.

These results support the use of "add-on" hormone therapy with letrozole in postmenopausal women with hormone-sensitive early breast cancer, the team concludes.